Method of making electrical connections



Dec. 12, 1939. R. LUNSFORD 2,132,953

METHOD OF MAKING ELECTRICAL CONNECTIONS 2 Sheets-Sheet 1 Filed Feb. 28, 1955 6/ FIG. 7 :5 2/ i2 INVENTOR R. L. LUNSFORD ATTORNEY Dec. 12, 1939. LUNSFORD 2,182,968

METHOD OF MAKING ELECTRICAL CONNECTIONS 2 Sheets-Sheet 2 Filed Feb. 28, 1935 FIG. 9

Y 2 INVENTOR R. L.LUN5FORD ATTORNE Y multipling Patented Dec. 12, 1939 UNITED STATES PATENT OFFICE LIETHOD OF MAKING ELECTRICAL CONNECTIONS Robert L. Lunsiord, Belleville, N.

J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation or New York Application February 28, 1935, Serial No.

6 Claims.

This invention relates to methods of making electrical connections and particularly to methods for making multiple switchboards.

The objects of the and improve the methods nections; and to effect a saving of time connections in telephone invention are to simplify of making cable conand labor in the process of multipling switchboard terminals.

Connecting cables for multipling the terminal sets in a telephone switchboard have been devised heretofore in which a plurality of flexible conductors and threads of some insulating material, such as cotton, are woven together in a flat band or ribbon, the conductors being exposed at proper intervals to permit of their connection to the terminal sets which it is desired to connect in multiple relation. A cable of this type is shown in the patent to McBerty No. 1,054,784 of March According to the present invention advantages are obtained over these prior multipling devices by the use of a unitary cable structure in which a plurality of bare w ire conductors are held in spaced parallel relation by a series of insulating bonds arranged at suitably spaced intervals along the length of said conductors, each bond comprising a strip of insulating material placed on one side of said conductors and secured to them by some suitable adhesive material such as thermoplastic cement.

A feature of the invention is a method of sists in providing said switchboard terminal sets which conterminals with notches or recesses, arranging said terminals with notches in line, preparing a connecting cable by fixing a plurality of bare conductors in spaced relation to each other, placing a series of insulating members in proximity to said vals along the length ductors to said insulating onductors at spaced interthereof, securing said conmembers by the application of a cementing substance to form a unitary cable structure, placing said cable in position with the conductors of said terminals, and securing said terminals.

Another feature of of multipling thereof in the notches said conductors to the invention is the method switchboard terminals in which the connecting cable is prepared by fixing a plurality of bare wire conductors in spaced relation to each other, placing a seri spaced es of insulating strips in relation along one side of said conductors,

placing a second series of insulating strips in spaced relation along ductors, and opposing the other side of said conthe insulating strips of said first series, cementing the opposing strips together to form bonds holding said conductors, and applying said conductors to the terminals to be multipled.

These and be described more fully in the following specification which should be considered in connection with the accompanying drawings.

Referring to the drawings:

Fig. 1 shows a portion of a cable structure made in accordance with this invention;

Fig. 2 is a cross-section of the cable structure shown in Fig. 1;

Fig. 3 shows structure;

Fig. 4 is a cross-section of the cable structure shown in Fig. 3;

Fig. 5 illustrates a modification of the cable structure shown in Fig. 4;

an alternative form 0! the cable Figs. 6 and '7 show two views of a cable in the process of manufacture;

Fig. 8 illustrates the manner in which the completed cable structure is applied to the sets of terminals to be multipled; and

Figs. 9 and 10 illustrate adjacent switches or switchboards connected in multiple by means of the connecting cables.

The connecting cables to relates are particularly which this invention useful for connecting in multiple the successive sets of electrical terminals in automatic switches and switchboards for telephone systems. These cables may be applied to various types of automatic switches and switchboards, such as those illustrated in the patent to F. Aldendorff 1,663,230 of March 20, 1928; in

the patent to J. N. Reynolds 1,139,722 of May 18, 1915; and in the application of J. N. Reynolds, Serial No. 702,453 filed December 15, 1933, issued as Patent 2,021,329, Nov. 19, 1935.

The method of multipling switchboard termisingle unit as many parallel strap wires as there are terminals in each of the sets to be multiplied. The wires are held in fixed spaced relation by insulating bonds which occur at suitable intervals along the length of the wires. The structure thus formed is rigid, and when applied and, solother features of the invention will 5 time and skill on the 45 may be made of any suitable insulating material,

such as cellulose acetate, cellulose nitrate, or phenol fibre. These bonds are applied to one side of the conductors, and the conductors are cemented to the bonds by means of suitable cementing material. For this purpose a lacquer may be used such as that commonly employed for insulating the butts of electric cables. Also, a cement of the thermoplastic type may be used to advantage. Cements oi this type may be derived by treating such substances as cellulose acetate or cellulose nitrate with some plasticizing substance.

The strap wires I, 2, 3 and 4 are thus secured to the bond strip 5 by portions 1, 8, 9 and I0 01' the cement, and likewise they are secured to the bond strip 6 by portions I I, l2, l3 and I4 01 the cement. While only four conductors are shown in the structure of Fig. 1, it is obvious that the number oi conductors in the cable can be varied and will depend upon the number of terminals in the sets to be multipled. It is also apparent that the spacing of the insulating strips may be varied in accordance with the requirements.

In the'connecting cable shown in Figs. 3 and 4, the strap wires I5, I76, I! and I8 are secured in spaced relation by a somewhat different form 01 insulating bond. In this case each of the bonds consists of a pair of insulating strips i9 and 20 placed on opposite sides of the conductors and cemented to each other and to the conductors by means oi. some suitable cementing substance such as that described in connection with Fig. 1.

One method 01 manufacturing these connecting cables is illustrated in Figs. 6 and 7. The desired number of strap wires 2|, 22, 23, 24, 25, 28, are drawn from spools mounted on shafts 27, 28 and 29 through a spacing guide 30 and between the members 3| and 32 of a, press and are temporarily held under suitable tension by a holding device or jig having members 60 and 6|. The two insulating strips 33 and 34 of a bond are placed on opposite sides of the strap wires between the press members, and the proper amount of cement 35 is placed between the insulating strips. Either the cement alone or both the cement and the insulating strips 33 and 34 may be subjected to heat, and while in a heated condition the insulating strips are pressed together by the downward movement of the press member 32. The cable structure isthen drawn forward the proper distance, and the next bond is similarly formed.

Another modification of the method of making the cable is to flx the wires in a jig and provide a series 01' presses along the length thereof so that a plurality of bonds can be made simultaneously,

It is obvious that the single insulating strip bond shown in Fig. 1 can be made by these and other modifications of the method.

By using a thermoplastic cement such as one having a cellulose nitrate base, a quick drying action is attained. These cements are plastic,

when subjected to heat and harden or dry rapidly when the temperature is lowered- I des r the drying action of the cement can be hastened by applying a blast 01' cold air to the bond either before or after it has been withdrawn from the press 3|, 32.

The bondsshown in Figs. 3 and 4 and the bonds 38 and 31 are formed by applying pressure sumcient to bring the opposing insulating strips to a point where they are separated by a thin layer of the cementing substance, but not sufllcient to bring them into physical engagement with each other. If desirable the opposing insulating strips and the applied cementing substance may be subjected to sufilcient pressure and temperature to substantially weld them together. Fig. 5 shows an insulating bond made 'in this manner.

The connecting cable can be prepared initially in lengths suitable for the multiple terminals to which it is to be applied, or it can be made in stock lengths and later cut to meet the requirements of the switch for which it is to be used.

Fig, 8 illustrates four sets of switch terminals 38, 39, 4B and 4|, each set comprising four individual terminals. Terminal sets 38 and 39 are in alignment with each other and with other terminal sets, not shown, constituting a row. Likewise, terminal sets 40 and 4| together with others, not shown, constitute a second row of terminals. These terminals are provided withnotches for receiving the multiple strap wires, and the notches of corresponding terminals in each of the successive sets in a row are in alignment with each other. This alignment is secured as shown in the figure by progressively oifsetting the notches of the several terminals in each set. After the cable lengths 42 and 43 have been prepared, they are applied to the terminals as seen in Fig. 8 with each of the several strap conductors resting in the aligned notches oi. the corresponding terminals of the successive sets. Following this, the strap conductors are soldered to the terminals at the several points 01' contact in the respective notches.

In Fig. 9 two switches or switchboards 44 and 45 are mounted in line with each other. Here it is necessary not only to multiple the succes sive terminal sets in each switchboard but also to extend the multiple from one switchboard to the next. This is accomplished by preparing the connecting cables 46, 41, 48, etc., in sufllcient lengths to extend across as many of the separate switchboards 44, 45, etc., as it is necessary to include in the multiple.

Fig. 10 shows two adjacent switches or switchboards 49 and 1 50 and illustrates a diilerent method of joining the multiple of one switchboard to another. In this arrangement the terminal sets of switchboard 49 are multipled by the connecting cables 5|, 52, 53, etc.; and the terminal sets of switchboard 50 are multipled by the connecting cables 54, 55, 56, etc.; and corresponding connecting cables of the two switchboards are joined together by the short jumper wires 51, 58, etc.

In both Figs. 9 and 10 the exposed conductors between the adjacent switches may be covered with some suitable insulating varnish.

What is claimed is:

1. The method of connecting a plurality of electrical terminal sets in multipled relation which comprises providing the individual terminals oi said sets with recesses, arranging said temiinals with the recesses thereof in line, preparing a connecting cable by arranging a plurality of conductors in spaced relation, placing a. series of insulating members in proximity to said conductors, cementing said insulating members to said conductors to form a unitary cable structure, applying said cable structure to said termi- 2. The method of connecting nal sets in multiple relation which comprises providing the individual terminals of each set with notches, arranging the corresponding terminals in the several sets with their notches in line, preparing a connecting cable by arranging a plurality of bare wire conductors in spaced parallel relation, placing a series of insulating strips in spaced relation along one side of said conductors, placing a second series of insulating strips in spaced relation along the other side of said conductors and opposing the insulating strips of said first series, cementing the opposite strips together to form bonds holding said conductors, applying said conductors to said terminal sets in such a way that each conductor rests in the notches of corresponding terminals of the successive sets, and securing said conductors to said terminals.

3. The method of multipling the terminal sets of a switchboard which comprises providing the terminals of said sets with recesses, arranging said terminals with the recesses in line, preparing a connecting cable by arranging a plurality of bare wire conductors in spaced relation, placing a series of insulating strips in proximity to said conductors along the length thereof, cementing said insulating strips to said wire conductors to form a unitary cable structure, cutting said cable structure to suitable lengths, applying the prepared structure to said terminals with the wire conductorsthereof resting in the recesses of said terminals, and soldering said conductors to said terminals.

4. The method of connecting a plurality of electrical terminal sets in multiple relation which comprises providing the individual terminals of said sets with recesses, arranging said terminals cement said with the recesses thereof in line, preparing a connecting cable by arranging a plurality of conductors in spaced relation, placing a series of in- 'sulating members in proximity to said conductors, securing said insulating members to said conductors with a thermo-plastic substance to form a unitary cable structure, applying said cable structure to said terminals, and securing said conductors to said terminals in the recesses thereof.

5. The method of connecting a plurality of electrical terminal sets in multiple relation which comprises providing the individual terminal sets with recesses, arranging said terminals with the recesses in line, preparing a connecting cable by arranging a plurality of bare wires in spaced relation, placing a series of insulating members in proximity to said wires, subjecting said insulating members to heat to cement said wires thereto to form a unitary cable structure, applying said cable structure to said terminals with the wires resting in said recesses, and securing said wires to said terminals.

6. The method of connecting a plurality of terminal sets in multiple relation which comprises providing the individual terminals of said sets with apertures, arranging said terminals with the apertures thereof in line, preparing a connecting cable by arranging a plurality of bare conductors in spaced relation, placing a series of insulating strips in proximity to said conductors at spaced thermo-plastic substance on said insulating strips at the points of proximity subjecting said insulating strips and thermoplastic substance to temperature and pressure to insulating strips to said conductors to form a unitary cable structure, applying said cable structure to said terminals with the conductors resting in said apertures, and securing said conductors to said terminals.

ROBERT L. LUNSFORD. 

